The first British nuclear test, Hurricane was detonated in a lagoon on Trimouille Island. The bomb was exploded inside the frigate HMS Plym which was anchored in 12 m of water. The device was a plutonium implosion bomb similar to the Fat Man using plutonium produced at Windscale (now Sellafield).The test was devised to investigate the effects of a ship-smuggled bomb. The ship was mostly vaporized by the explosion, except for pieces of hot metal that set fires to the spinifex scrub covering Trimouille. The explosion left a crater on the seabed 6m deep and 304m wide.The cloud rose only to 4572m due to the very dry air which allowed evaporation of water to cool the ascending cloud, and a strong inversion at that altitude.